﻿#include<iostream>
using namespace std;
int exam1_1_1()
{
	double x1, x2, y1, y2;
	double dx, dy;
	cin >> x1 >> y1 >> x2 >> y2;
	if (x1 > x2)
	{
		dx = x1 - x2;
	}
	else
		dx = x2 - x1;
	if (y1 > y2)
	{
		dy = y1 - y2;
	}
	else
		dy = y2 - y1;
	cout << dx + dy << endl;
	return 0;
}